Process of preparing solid developer for electrostatic latent images

ABSTRACT

A PROCESS FOR THE PREPARATION OF A SOLID ELECTROSTATOGRAPHIC DEVELOPER MATERIAL COMPRISING PROVIDING TONER PARTICLES CAPABLE OF BEING ELECTROSTATICALLY COATED ON A CARRIER SURFACE, THE TONER PARTICLES HAVING A BLOCKING TEMPERATURE OF AT LEAST ABOUT 110*F., A MELT VISCOSITY LESS THAN ABOUT 2.5X10**-4 POISE AT TEMPERATURES UP TO ABOUT 450*F., THE TONER PARTICLES INCLUDING A COLORANT, A THERMOPLASTIC RESIN, A SOLID ADDITIVE HAVING A MELTING POINT BETWEEN ABOUT 115*F. AND 270*F., FORMING THE TONER PARTICLES INTO PARTICLES HAVING A SIZE RANGE OF UP TO ABOUT 30 MICRONS, AND THERE AFTER TUMBLING THE PARTICLES WITH FROM ABOUT 0.002 PERCENT TO ABOUT 20 PERCENT BY WEIGHT, BASED ON THE WEIGHT OF THE PARTICLES, OF AT LEAST ONE SOLID, STABLE HYDROPHOBIC METAL SALT OF A FATTY ACID UNTIL THE METAL SALT IN UNIFORMLY MIXED WITH AND IS AVAILABLE AT THE EXTERNAL SURFACES OF THE PARTICLES.

United States Patent Ofice 3,740,334 Patented June 19, 1973 3,740,334PROCESS OF PREPARING SOLID DEVELOPER FOR ELECTROSTATIC LATENT IMAGESBurton B. Jacknow and Joseph H. Moriconi, Rochester, N.Y., assignors toXerox Corporation, Rochester, N .Y.

No Drawing. Original application Aug. 28, 1970, Ser. No.

68,019, now Patent No. 3,653,893. Divided and this application Nov. 8,1971, Ser. No. 196,700

Int. Cl. G03g 9/02 U.S. Cl. 252-621 8 Claims ABSTRACT OF THE DISCLOSUREA process for the preparation of a solid electrostatographic developermaterial comprising providing toner particles capable of beingelectrostatically coated on a carrier surface, the toner particleshaving a blocking temperature of at least about 110 F., a melt viscosityless than about 2.5 10' poise at temperatures up to about 450 F., thetoner particles including a colorant, a thermoplastic resin, a solidadditive having a melting point between about 115 F. and about 270 F.;forming the toner particles into particles having a size range of up toabout 30 microns, and thereafter tumbling the particles with from about0.002 percent to about 20 percent by weight, based on the Weight of theparticles, of at least one solid, stable hydrophobic metal salt of afatty acid until the metal salt is uniformly mixed with and is availableat the external surfaces of the particles.

This is a division of application Ser. No. 68,019, filed Aug. 28, 1970,now U.S. Pat. No. 3,653,893.

BACKGROUND OF THE INVENTION This invention relates to imaging systems,and more particularly, to improved xerographic developing materials,their manufacture and use.

The formation and development of images on the surface of photoconductormaterials by electrostatic means is well known. The basic xerographicprocess, as taught by C. F. Carlson in U.S. Pat. 2,297,691, involvesplacing a uniform electrostatic charge on a photoconductive insulatinglayer, exposing the layer to a light-and-shadow image to dissipate thecharge on the areas of the layer exposed to the light and developing theresulting latent electrostatic image by depositing on the image a finelydivided electroscopic material referred to in the art as toner. Thetoner will normally be attracted to those areas of the layer whichretain a charge, thereby forming a toner image corresponding to thelatent electrostatic image. This powder image may then be transferred toa support surface such as paper. The'transferred image may subsequentlybe permanently affixed to the support surface as by heat. Instead oflatent image formation by uniformly charging the photoconductive layerand then exposing the layer to a light-and-shadow image, one may formthe latent image by directly charging the layer in image configuration.The powder image may be fixed to the photoconductive layer ifelimination of the powder image transfer step is desired. Other suitablefixing means such as solvent or overcoating treatment may be substitutedfor the foregoing heat fixing steps.

Several methods are known for applying the electroscopic particles tothe latent electrostatic image to be developed. One development method,as disclosed by E. N. Wise in U.S. Pat. 2,618,552, is known as cascadedevelopment. In this method, a developer material comprising relativelylarge carrier particles having finely divided toner particleselectrostatically coated thereon is conveyed to and rolled or cascadedacross the electrostatic latent image bearing surface. The compositionof the carrier particles is so selected as to'triboelectrically chargethe toner particles to the desired polarity. As the mixture cascades orrolls across the image bearing surface, the toner particles areelectrostatically deposited and secured to the charged portion of thelatent image and are not deposited on the uncharged or backgroundportions of the image. Most of the toner particles accidentallydeposited in the background are removed by the rolling carrier, dueapparently, to the greater electrostatic attraction between the tonerand the carrier than between the toner and the discharged background.The carrier and excess toner are then recycled. This technique isextremely good for the development of line copy images.

Another method of developing electrostatic images is the magnetic brushprocess as disclosed, for example, in U.S. Pat. 2,874,063. In thismethod, a developer material containing toner and magnetic carrierparticles are carried by a magnet. The magnetic field of the magnetcauses alignment of the magnetic carrier into a brush-likeconfiguration. This magnetic brush is engaged with the electrostaticimage-bearing surface and the toner particles are drawn from the brushto the latent image by electrostatic attraction.

Still another technique for developing electrostatic latent images isthe powder cloud process as disclosed, for example, by C. F. Carlson inU.S. P'at. 2,221,776. In this method, a developer material comprisingelectrically charged toner particles in a gaseous fluid is passedadjacent the surface bearing the latent electrostatic image. The tonerparticles are drawn by electrostatic attraction from the gas to thelatent image. This process is particularly useful in continuous tonedevelopment.

Other development methods such as touchdown development as disclosed byR. W. Gundlach in U.S. Pat. 3,166,432 may be used where suitable.

Although some of the foregoing development techniques are employedcommercially today, and most Widely used commercial xerographicdevelopment technique is the technique known as' cascade development. Ageneral purpose oflice copying machine incorporating this developmentprocess is described in U.S. Pat. 3,099,943. The cascade technique isgenerally carried out in a commercial apparatus by cascading a developermixture over the upper surface of an electrostatic latent image-bearingdrum having a horizontal axis. The developer is transported from atrough or sump to the upper portion of the drum by means of an endlessbelt conveyor. The developer is cascaded downward along a portion of thesurface of the drum into the sump and is subsequently recycled throughthe developing system to develop additional electrostatic latent images.Small quantities of toner are periodically added to the developingmixture to compensate for the toner depleted by development. Thisprocess is then repeated for each copy produced by the machine and isordinarily repeated many thousands of times during the usable life ofthe developer.

Thus, it is apparent from the description presented above as well as inother development techniques, that the toner is subjected to mechanicalattrition which tends to break down the particles into undesirable dustfines. Toner fines are detrimental to machine operation because they areextremely difficult to remove from reusable imaging surfaces and alsobecause they tend to drift to other parts of the machine and deposit oncritical machine parts such as optical lenses. The formation of fines isretarded when the toner contains a tough, high molecular weight resinwhich is capable of withstanding the shear and impact forces imparted tothe toner in the machine. Unfortunately, many high molecular weightmaterials cannot be employed in high speed automatic machines becausethey cannot be rapidly fused during a powder image heat fixing step.Attempts to rapidly fuse a high melting point toner by means ofoversized high capacity heating units have been confronted with theproblems of preventing the charring of paper receiving sheets and ofadequately dissipating the heat evolved from the fusing unit or units.Thus, in order to avoid charring or combustion, additional equipmentsuch as complex and expensive cooling units are necessary to properlydispose of the large quantity of heat generated by the fuser. Incompleteremoval of the heat evolved will result in operator discomfort anddamage to heat sensitive machine components. Further, the increasedspace occupied by and the high operating cost of the heating and coolingunits, often outweigh the advantages achieved by the increased machinespeed. On the other hand, low molecular weight resins which are easilyheat fused at relatively low temperatures are often undesirable becausethese materials tend to form thick films on reusable photoconductorsurfaces. These films tend to cause image degradation and contribute tomachine maintenance down time. In addition, low molecular weight resinstend to form tacky images on the copy sheet which often offset to otheradjacent sheets. Further, toner particles containing low molecularweight resins tend to bridge, cake and block in the shipping containeras well as in the xerographic machine. Also, the toner material must becapable of accepting a charge of the correct polarity when brought intorubbing contact with the surface of carrier materials in cascade,magnetic brush or touchdown development systems. Some resinous materialswhich possess many properties which would be desirable in xerographictoners dispense poorly and cannot be used in automatic copying andduplicating machines. Other resins dispense well but form images whichare characterized by low density, poor resolution, or high background.Further, some resins are unsuitable for processes where electrostatictransfer is employed. Since most thermoplastic materials are deficientin one or more of the above areas, there is a continuing need forimproved toners and developers.

SUMMARY OF THE INVENTION It is, therefore, an object of this inventionto provide a toner overcoming the above noted deficiencies.

It is another object of this invention to provide a toner which isresistant to film formation when employed in conventional xerographiccopying and duplicating devices.

It is another object of this invention to provide a xerographic tonerwhich forms images having reduced background.

It is another object of this invention to provide a free flowing tonerwhich is resistant to agglomeration.

It is another object of this invention to provide a xerographic tonerwhich can be fused at higher rates with less heat energy.

It is another object of this invention to provide a xerographic tonerwhich forms high resolution images.

It is another object of this invention to provide a xerographic tonerwhich is resistant to mechanical attrition during the developmentprocess.

It is another object of this invention to provide a xerographic tonerhaving improved dispensing characteristics.

It is another object of this invention to provide a toner and developerhaving physical and chemical properties superior to those of knowntoners and developers.

The above objects and others are accomplished by providing afinely-divided low melting toner comprising a colorant, a thermoplasticresin comprising a vinyl resin, a solid metal salt of a fatty acid and asolid additive having a melting point between about 115 F. to about 270F. and having the general structures 1) r TI) -o l'l wherei n p se ts apqsitivs i t g twin 3 to 7 i c usive and R represents an organic moietyhaving from 3 to 12 carbon atoms,

Cllnl wherein n represents a positive integer from 0 to 3 inclusive andm has an average value from 0.5 to 2.5 inclusive. For optimum operationin high speed xerographic machines employing paper receiving webs, thetoner should have a melting range between about F. to about 300 F. and amelt viscosity of less than about 2.0 l0- poise up to temperatures ofabout 300 F. Toner melting temperatures below about 300 F. are preferredbecause heat dissipation and paper degradation problems are avoided. Thedevelopers of this invention contain from about 0.02 percent to about 20percent by weight, based on the weight of the toner in the finaldeveloper mixture, of the solid hydrophobic metal salt of a higher fattyacid. Preferably, the developers of this invention contain from about0.05 to about 4 percent by weight of the metal salt because maximumreduction of background deposits, improved image density and higherimage character resolution are achieved. Without the presence of a solidstable hydrophobic metal salt of a higher fatty acid in the developer,extremely rapid degradation of reusable imaging surfaces, untenably highbackground, reduced toner image density, poor toner image transfer,reduced carrier particle life, increased difficulty in removing residualtoner material from reusable imaging surfaces, and reduced electricalstability occurs. Although the initial electrostatic imaging surfacepotential may be reduced and abrasion resistance improved when theproportion of metal salt present is increased above about 10 percent,undesirable background deposits increase noticeably. If the chargevoltage is reduced to compensate for the presence of metal salt inexcess of about 10 percent, the images begin to acquire a washed outappearance. It is not essential that the entire surface of each tonerparticle be coated with the metal salt, e.g., sufficient metal salt ispresent when about 10 to about 16 percent of the toner particle surfacesare coated with a metal salt. When the metal salt is dispersed in ratherthan coated on a toner or carrier particle, proportionately more metalsalt is necessary in order to maintain a sufficient quantity of theexposed salt at the surface of the toner or carrier particle. Theadditional amount of metal salt necessary depends to a large extent onthe surface area of the developer particles, hence upon the particlediameter selected. Any suitable stable solid hydrophobic metal salt of afatty acid having a melting point greater than about 57 C. may beemployed. Optimum results are obtained when about 0.05 to about 4percent by weight, based on the weight of the toner, of zinc stearate isavailable at the outer surfaces of the particles in the developingmaterial. The developers of this invention containing zinc stearate arepreferred because the resulting mixture is characterized by outstandingfusing rates, high cleanability from electrostatic imaging surfaces,greater triboelectric stability, denser toner images and increasedresistance to mechanical attrition. Unexpectedly, both the fire hazardand excessive power consumption problems encountered in high speed xero-R @1111 also be more than 1 substltuen uch. a 2 chlcrlnes e 6' y graphicdevelopment processes are obviated when toners containing the abovedescribed polymeric esterification product and metal salt are employed.

Any suitable vinyl resin having a melting point of at least about 110 F.may be employed in the toners of this invention. The vinyl resin may bea homopolymer or a copolymer of two or more vinyl monomers. Typicalmonomeric units which may be employed to form vinyl polymers include:styrene, p-chlorostyrene; vinyl naphthalene; ethylenically unsaturatedmono-olefins such as ehtylene, propylene, butylene, isobutylene and thelike; vinyl esters such as vinyl chloride, vinyl bromide, vinylfluoride, vinyl acetate, vinyl propionate, vinyl benzoate, vinylbutyrate and the like; esters of alphamethylene aliphatic monocarboxylicacids such as methyl acrylate, ethyl acrylate, nbutylacrylate, isobutylacrylate, dodecyl acrylate, n-octyl acrylate, 2-chloroethyl acrylate,phenyl acrylate, methylalpha-chloroacrylate, methyl methacrylate, ethylmeth acrylate, butyl methacrylate and the like; acrylonitrile,methacrylonitrile, acrylamide, vinyl ethers such as vinyl methyl ether,vinyl isobutyl ether, vinyl ethyl ether, and the like; vinyl ketonessuch as vinyl methyl ketone, vinyl hexyl ketone, methyl isopropenylketone and the like; vinylidene halides such as vinylidene chloride,vinylidene chlorofiuoride and the like; and N-vinyl compounds such asN-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole, N- vinyl pyrrolideneand the like; and mixtures thereof. Generally, suitable vinyl resinsemployed in the toner have a weight average molecular weight betweenabout 3,000 to about 500,000.

Toner resins containing a relatively high percentage of a styrene resinsare preferred. The presence of a styrene resin is preferred because agreater degree of image definition is achieved with a given quantity ofadditive material. Further, denser images are obtained when at leastabout 25 percent by weight, based on the total weight of resin in thetoner, of a styrene resin is present in the toner. The styrene resin maybe a homopolymer of styrene or styrene homologues or copolymers ofstyrene with other monomeric groups containing a single methylene groupattached to a carbon atom by a double bond. Thus, typical monomericmaterials which may be copolymerized With styrene by additionpolymerization include: p-chlorostyrene; vinyl naphthalene;ethylenically unsaturated mono-olefins such as ethylene, propylene,butylene, isobutylene and the like; vinyl esters such as vinyl chloride,vinyl bromide, vinyl fluoride, vinyl acetate, vinyl propionate, vinylbenzoate, vinyl butyrate and the like; esters of alpha-methylenealiphatic monocarboxylic acids such as methyl acrylate, ethyl acrylate,n-butylacrylate, isobutyl acrylate, dodecyl acrylate, n-octyl acrylate,2-chloroethyl acrylate, phenyl acrylate, methyl alpha-chloroacrylate,methyl methacrylate, ethyl methacrylate, butyl meth acrylate and thelike; acrylonitrile, methacrylonitrile, acrylamide, vinyl ethers such asvinyl methyl ether, vinyl isobutyl ether, vinyl ethyl ether, and thelike; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone,methyl isopropenyl ketone and the like; vinylidene halides such asvinylidene chloride, vinylidene chlorofluoride and the like; and N-vinylcompounds such as N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole,N-vinyl pyrrolidene and the like; and mixtures thereof. The styreneresins may also be formed by the polymerization of mixtures of two ormore of these unsaturated monomeric materials with a styrene monomer.The expression addition polymerization is intended to include knownpolymerization techniques such as free radical, anionic and cationicpolymerization processes.

The vinyl resins, including styrene type resins, may also be blendedwith one or more other resins if desired. When the vinyl resin isblended with another resin, the added resin is preferably another vinylresin because the resulting blend is characterized by especially goodtriboelectric stability and uniform resistance against physicaldegradation. The vinyl resins employed for blending with etc the styrenetype or other vinyl resin may be prepared by the addition polymerizationof any suitable vinyl monomer such as the vinyl monomers describedabove. Other thermoplastic resins may also be blended with the vinylresins of this invention. Typical non-vinyl type thermoplastic resinsinclude: rosin modified phenol formaldehyde resins, oil modified epoxyresins, polyurethane resins, cellulosic resins, polyether resins andmixtures thereof. When the resin component of the toner contains styrenecoypolymerized with another unsaturated monomer or a blend ofpolystyrene and another resin, a styrene component of at least about 25percent, by weight, based on the total weight of the resin present inthe toner is preferred because denser images are obtained and a greaterdegree of image definition is achieved with a given quantity of additivematerial.

The combination of the resin component, colorant and additive, whetherthe resin component is a homopolymer, copolymer or blend, should have ablocking temperature of at least about F and a melt viscosity of lessthan about 2.5 X 10" poise at temperatures up to about 450 F. When thetoner is characterized by a blocking temperature less than about 110 F.the toner particles tend to agglomerate during storage and machineoperation and also form undesirable films on the surface of reusablephotoreceptors which adversely affect image quality. If the meltviscosity of the toner is greater than about 2.5 10" poise attemperatures above about 450 F., the toner material of this inventiondoes not adhere properly to a receiving sheet even under conventionalxerographic machine fusing conditions and may easily be removed byrubbing.

The solid toner additives of this invention may be selected from threedifferent groups of organic compounds. In the first group, the compoundshave the general structure:

ROO

wherein n represents a positive integer from 3 to 7 inclusive and Rrepresents an organic moiety having from 3 to 12 carbon atoms. Typicalcompounds represented by this formula include: pentaerythritoltetrabenzoate, sucrose benzoate, triethylene glycol dibenzoate, glyceryltribenzoate, neopentylglycol dibenzoate, trimethylolethane tribenzoate,and the like. Outstanding results have been obtained when the additiveis pentaerythritol tetrabenzoate. When the additive is pentaerythritoltetrabenzoate, the advantages obtained in blocking resistance, lowertendency to film and optimum fusing temperatures are supplemented bysharp, high-contrast copies having little or no background deposits. Thenegligible background deposits in the ultimate copy appear to be due toa markedly reduced tendency of the toner to adhere to the backgroundareas of a photoconductor during development. Thus, toners containingpentaerythritol tetrabenzoate are the preferred toners in thisinvention. Compounds in the second group having the general structure:

ill. Q 4;

2 R can also be more than 1 substituent, such as 2 chlorinessulfonamide, o-toluene sulfonamide, p-toluene sulfonamide,N,N-di-p-hydroxyethyl-p-toluene sulfonamide, N, N-dimethyl benzenesulfonamide, N-cyclohexyl benzene sulfonamide, N-cyclohexyl 3,4dichlorobenzene sulfonamide, N-allyl p-toluene sulfonamide,N,N-di-p-hydroxyethyl p-toluene sulfonamide, N-cyclohexyl p-toluenesulfonamide and the like. Compounds representative of the third grouphaving the general structure:

wherein n represents a positive integer from to 3 inelusive and in hasan average value from 0.5 to 2.5 inclusive. Typical polychlorinatedpolyphenyl compounds represented by this formula include: p,p-dichlorobiphenyl; 2,4,7,9-tetrachloro biphenyl; 1,4 bis (p-chlorophenyl)-2chlorobenzene; 2,2 dichloro-4,4' (p-chlorophenyl) biphenyl and the like.Some of these compounds are sold under the Aroclor trademark by theMonsanto Company, St. Louis, Mo., and under the Halowax trademark by theKoppers Company, Inc., Pittsburgh, Pa., for example, Aroclor 2565,Aroclor 4465, Aroclor 5442, Aroclor 5460 and Halowax 0077. Preferably,the additive is employed in an amount from about 5 percent to about 55percent, by weight, based on the total weight of the resinous componentof the toner. As the relative quantity of additive in the toner isincreased above about 65 percent, the mechanical strength, creepresistance and permanency of the ultimate fused toner image begins todecrease rapidly. Thus, when brittle, non-polymeric compounds such asthe compounds disclosed in US. Pat. 3,272,644 are employed in automaticcopying and duplieating machines, extensive toner dust is formed and thefused toner images tend to crumble and flake off receiving sheets whenthe sheets are folded Further, some solid non-polymeric materials tendto vaporize or sublime and form toxic or flammable fumes. When less thanabout 3 percent of the additive is employed in the toner, the tonerfusing, flow and triboelectric properties are substantially the same asa toner which does not contain the additives. If desired, mixtures ofadditives may be employed in the toner. An increase in the relativequantity of additive tends to reduce the melt viscosity of the ultimatetoner.

It is to be understood that the specific formulas given for the unitscontained in the additives and resins of this invention represent thevast majority of the units present, but do not exclude the presence ofother monomeric units or reactants than those which have been shown. Forexample, some commercial materials such as polystyrenes, andpolychlorinated polyphenyl compounds contain trace amounts of homologuesor unreacted or partially reacted monomers. Any minor amount of suchsubstituents may be present in the materials of this invention.

Any suitable stable solid hydrophobic metal salt of a fatty acid havinga melting point greater than about 57 C. may be employed with the tonerresin of this invention. The metal salt should be substantiallyinsoluble in Water. Water soluble metal salts lack the proper electricalproperties and are adversely affected by humidity changes normallyoccurring in the ambient atmosphere. However, a large proportion ofsalts commonly regarded as insoluble, actually dissolve to a slightextent. To effectively carry out the purposes of this invention, thesolubility of the salt should be negligible. The salts having thedesired specific characteristics include many salts of linear saturatedfatty acids, unsaturated fatty acids, partially hydrogenated fatty acidsand substituted fatty acids and mixtures thereof. The metal salts may betumbled or milled with the toner or carrier particles or intimatelydispersed in each toner or carrier particle. However, the latterembodiment is less desirable than the tumbled or milled mixtures becausea greater q y f metal salt is required to provide a suflicient quantityof metal salt, exposed at the surface of the developer particles. Themetal salts are preferably mixed with toner material by tumblingpreformed finely divided metal salt particles with preformed finelydivided toner particles. The tumbling process is continued until thepreformed metal salt particles are uniformly distributed throughout themass of toner particles. Excellent toner mixtures are obtained when thepreformed toner particles are tumbled with preformed metal saltparticels having a size range between about 0.5 to about 50 microns. Thetumbled mixtures are preferred because the resulting treated tonersexhibit extremely stable imaging characteristics under widelyfluctuating humidity conditions.

Typical fatty acids from which stable solid hydrophobic metal salts maybe derived include: caproic acid, enanthylic acid, caprylic acid,pelargonic acid, capric acid, undecylic acid, lauric acid, tridecoicacid, myristic acid, pentadecanoic acid, palmitic acid, margaric acid,stearic acid, nondecylic acid, arachidic acid, beh'enic acid, stillingicacid, palmitoleic acid, oleic acd, ricinoleic acid, petroselinic acid,vaccenic acid, linoleic acid, linolenic acid, eleostearic acid, licanicacid, parinaric acid, gad-oleic acid, arachidonic acid, cetoleic acidand mixtures thereof. Typical stable solid metal salts of fatty acidsinclude: cadmium stearate, barium stearate, lead stearate, ironstearate, nickel stearate, cobalt stearate, copper stearate, strontiumstearate, calcium stearate, cadmium stearate, magnesium stearate, zincoleate, manganese oleate, iron oleate, cobalt oleate, copper oleate,lead oleate, magnesium oleate, zinc palmitate, cobalt palmitate, copperpalmitate, magnesium palmitate, aluminum palmitate, calcium palmitate,lead caprylate, lead caproate, zinc linoleate, cobalt linoleate, calciumlinoleate, zinc ricinoleate, cadmium ricinoleate and mixtures thereof.

Where the solid hydrophobic metal salt of a higher fatty acid is to bephysically mixed with or applied as a coating on toner or carrierparticles, the metal salt is preferably present in an amount from about0.02% to about 10% based on the weight of the toner in the finaldeveloper mixture. Optimum results are obtained with about 0.05 to about4% of the metal salt. Although the initial electrostatic imaging surfacepotential may be reduced and abrasion resistance improved when theproportion of metal salt present is increased above about 10%,undesirable background deposits increase noticeably. If the chargevoltage is reduced to compensate for the presence of metal salt inexcess of about 10%, the images begin to acquire a washed outappearance. It is not essential that the entire surface of each tonerparticle be coated with the metal salt, e.g., suflicient metal salt ispresent when 10 to 16% of the toner particle surfaces are coated with' ametal salt. When the metal salt is dispersed in rather than coated on atoner or carrier particle, proportionally more metal salt is necessaryin order to maintain a sufficient quantity of exposed salt at thesurface of the toner or carrier particle. The additional amount of metalsalt necessary depends to a large extent on the surface area of theparticles, hence upon the particle diameter selected. The use of smallquantities of calcium stearate as a pigment wetting agent in zinc oxidedeveloping powders is known as disclosed by Greig in US. Pat. 3,053,688at column 5, line 41 and Greig et al. in Canadian Pat. 633,- 458 atcolumn 9, line 8. However, the quantity of calcium stearate used byGreig and Greig et al. to facilitate the wetting of pigments dispersedin zinc oxide developing powders is insufficient to provide an effectivequantity of exposed calcium stearate at the surface of the tonerparticle for the purposes of the instant invention. When less than about0.02% metal salt based on the Weight of the toner is actually availableat the surface of the toner particle, its triboelectric, flow, abrasion,transfer and image forming properties are substantially the same as atoner or carrier which does not contain a metal salt of a fatty acid.Obviously, with a given quantity of metal salt based on the weight ofthe toner, a greater volume of the salt is available at the surface ofthe toner or carrier when the metal salt is added to a mixture ofpreformed colored toner particles or carriers than when it is intimatelydispersed Within each toner particle or carrier. If the concentration ofmetal salt is increased to the point where the toner consistsessentially of 100% metal salt, the metal salt will form slippery filmson the electrostatic image-bearing surface and carrier particles whichinterfere with powder image transfer, background removal and cleaning.US. Pat. 3,083,117 discloses a method of applying reactive tonerscontaining 100% iron stearate to an electrostatic image and thentransferring the developed image to a transfer sheet wet with analcoholic solution of gallic acid. The iron stearate reacts with thegallic acid to form a black reaction product. In addition to theproblems encountered when toner containing 100% metal salt is employed,electrostatic development methods of the foregoing type require liquidpre-treatment of the receiving sheet with an attendant increase in costand inconvenience. Further, curling, image bleeding, and offset, oftenoccur when moistened receiving sheets are used. Additional equipment todispose of toxic and inflammable fumes may also be necessary.

Excellent results have been obtained with zinc stearate. When the tonerand developer particles of this invention are treated with Zincstearate, particularly in the range of about 0.05 to about 4 percent byweight based on the total weight of toner, better flow, less background,higher density images at lower initial charging voltages, and highermachine speeds with less power are achieved. Drum Wear is markedlyreduced.

Any suitable pigment or dye may be employed as the colorant for thetoner particles. Toner colorants are well known and include, forexample, carbon black, nigrosine dye, aniline blue, Calco Oil Blue,chrome yellow, ultra marine blue, Du Pont Oil Red, Quinoline Yellow,methylene blue chloride, phthalocyanine blue, Malachite Green Oxalate,lamp black, Rose Bengal and mixtures thereof. The pigment or dyes shouldbe present in the toner in a suflicient quantity to render it highlycolored so that it will form a clearly visible image on a recordingmember. Thus, for example, where conventional xerographic copies oftyped documents are desired, the toner may comprise a black pigment suchas carbon black or a black dye such as Amaplast Black dye, availablefrom the National Aniline Products, Inc. Preferably, the pigment isemployed in an amount from about 3 percent to about 20 percent, byweight, based on the total weight of the colored toner. If the tonercolorant employed is a dye, substantially smaller quantities of colorantmay be used.

The toner compositions of the present invention may be prepared by anywell known toner mixing and comminution technique. For example, theingredients may be thoroughly mixed by blending, mixing and milling thecomponents and thereafter micropulverizing the resulting mixture.Another well known technique for forming toner particles is to spray-drya ball-milled toner composition comprising a colorant, a resin and asolvent.

Generally, the degree of quality of toner fix at a given fusertemperature decreases with an increase in toner melt viscosity. Asdiscussed above, if the melt viscosity of the toners of this inventionis greater than about 2.5 poise at temperatures above about 450 F., thetoner materials do not adhere properly to a receiving sheet even underconventional xerographic machine fusing conditions. Thus, the meltviscosity value of the toners of this invention aids in thedetermination of the degree of flow and penetration of the toner intothe surface of a receiving substrate such as paper during the heatfixing step. The expression melt viscosity, as employed herein, is ameasure of the ratio of shear stress to shear rate in poise at a giventemperature. All viscosity measurements are determined with an InstronCapillary Rheometer, Model TTC.

When the toner mixtures of this invention are to be employed in acascade development process, the toner should have an average particlesize by weight percent less than about 30 microns and preferably betweenabout 4 and about 20 microns for optimum results. For use in powdercloud development methods, particle diameters of slightly less than 1micron are preferred.

Suitable coated and uncoated carrier materials for cascade developmentare well known in the art. The carrier particles comprise any suitablesolid material, provided that the carrier particles acquire a chargehaving an opposite polarity to that of the toner particles when broughtin close contact with the toner particles so that the toner particlesadhere to and surround the carrier particles. When a positivereproduction of the electrostatic images is desired, the carrierparticle is selected so that the toner particles acquire a charge havinga polarity opposite to that of the electrostatic image. Alternatively,if a reversal reproduction of the electrostatic image is desired, thecarrier is selected so that the toner particles acquire a charge havingthe same polarity as that of the electrostatic image. Thus, thematerials for the carrier particles are selected in accordance with itstriboelectric properties in respect to the electroscopic toner so thatwhen mixed or brought into mutual contact one component of the developeris charged positively if the other component is below the firstcomponent in the triboelectric series and negatively if the othercomponent is above the first component in a triboelectric series. Byproper selection of materials in accordance with their triboelectriceffects, the polarities of their charge when mixed are such that theelectroscopic toner particles adhere to and are coated on the surfacesof carrier particles and also adhere to that portion of theelectrostatic image-bearing surface having a greater attraction for thetoner than the carrier particles. Typical carriers include sodiumchloride, ammonium chloride, aluminum potassium chloride, Rochelle salt,sodium nitrate, aluminum nitrate, potassium chlorate, granular zircon,granular silicon, methyl methacrylate, glass, silicon dioxide and thelike. The carriers may be employed with or without a coating. Many ofthe foregoing and other typical carriers are described by L. Walkup etal. in Us. Pat. 2,638,416 and E. N. Wise in US. Pat. 2,618,552. Anultimate coated carrier particle diameter between about 50 microns toabout 1,000 microns is preferred because the carrier particles thenpossess sufiicient density and inertia to avoid adherence to theelectrostatic images during the cascade development process. Adherenceof carrier beads to xerographic drums is undesirable because of theformation of deep scratches on the surface during the imaging transferand drum cleaning steps, particularly where cleaning is accomplished bya web cleaner such as the Web disclosed by W. P. Graff, Jr. et al. inUS. Pat. 3,186,838. Also print deletion occurs when carrier beads adhereto xerographic imaging surfaces. Generally speaking, satisfactoryresults are obtained when about 1 part toner is used with about 10 to200 parts by weight of carrier.

The toner compositions of the instant invention may be employed todevelop latent electrostatic images on any suitable electrostatic latentimage-bearing surface including conventional photoconductive surfaces.Well known photoconductive materials include vitreous selenium, organicor inorganic photoconductors embedded in a nonphotoconductive matrix,organic or inorganic photoconductors embedded in a photoconductivematrix, or the like. Representative patents in which photoconductivematerials are disclosed include U.S. Pat. 2,803,542 to Ullrich, US. Pat.2,970,906 to Bixby, U.S. Pat. 3,121,006 to Middleton, US. Pat. 3,121,007to Middleton, and US. Pat. 3,151,982 to Corrsin.

DESCRIPTION OF PREFERRED EMBODIMENTS The following examples furtherdefine, describe and compare methods of preparing the toner materials ofthe 1 1 present invention and of utilizing them to develop electrostaticlatent images. Parts and percentages are by weight unless otherwiseindicated.

Example I A sample of Xerox 813 Toner particles sold by the XeroxCorporation, Rochester, N.Y. is employed as a control. Copies of astandard test pattern are made with the toner in a modified 813 Xeroxcopying machine. The fuser temperature is regulated with a proportionaltemperature controller and is monitored by means of a thermocouplemounted in the center of the upper fuser plate. The fuser plates aremounted about 0.75 inch apart. The toner images on 8 inch by 13 inchcopy sheets are trans ported through the fuser at the rate of 11 sheetsper minute which is twice the normal rate. Since the standard Xerox 813copy machine drive motor stalls and overheats when the machine isoperated at twice the normal operating speed, a motor having twice thepower output is employed. After passage through the fuser, the copysheets are fastened to a full page abrading cylinder having a diameterof about 4.75 inches. A conventional 813 cleaning web is pressed againstthe copy sheet by a spring loaded roller under a spring tension of about40 pounds. By rotating the cylinder bearing the copy sheet, the entiretoner image on the copy sheet is abraded by frictional contact with theweb. A minimum fuser temperature is established when all the testcharacters are legible after an abrasion run of revolutions of theabrading cylinder. Xerox 813 carrier beads are employed with the tonerduring the development step. The minimum fuser temperature at whichlegible copies are obtained with the 813 toner is found to be about 610F. Many of the copies leaving the fuser contain glowing embers and insome instances live flames. Micrograph studies of the reusable imagingsurface after 5,000 cycles reveals considerable wear and degradation ofthe surface.

Example II A toner mixture is prepared comprising about 7.5 parts byweight of a copolymer of about 65 parts by weight of styrene and 35parts by weight of butyl methacrylate; about 1.5 parts by weight ofpentaerythritol tetrabenzoate; and about 1 part by weight of carbonblack (Neo Spectra Mark II). The additive is a hard, dry solid having amelting range of about 201 to about 204 F. The toner mixture has anInstron Capillary Rheometer melt viscosity of about .5 poise at 255 F.After melting and preliminary mixing, the composition is fed into arubber mill and thoroughly milled to yield a uniformly dispersedcomposition of the additive in the thermoplastic resin body. Theresulting mixed composition is cooled and then finely subdivided in ajet pulverizer to yield toner particles having an average particle sizeby weight percent of about 10 to about 20 microns. About 1 part byweight of the pulverized toner particles are mixed with about 0.01 partby weight of zinc stearate particles having a size range from about 0.5to about 35 microns and about 99 parts by weight of 813 Xerox carrierbeads and substituted for the 813 developer in the testing machinedescribed in Example I. The treated toner dispenses well and highresolution images substantially free from background are obtained. Undersubstantially identical test conditions, it is found that the originalstandard Xerox 813 drive motor can be used and that the minimum fusertemperature at which legible copies are obtained after an abrasion runof 5 revolutions of the abrading cylinder is about 510 F. This is areduction of about 100 F. from the fuser temperature required for thecontrol sample of Example I. No live embers or flames are observed oncopies emerging from the fuser. No blocking is observed after a sampleof this toner is stored in an air circulating oven maintained at atemperature of about 110 F. for 24 hours.

1 2 Example III A toner mixture is prepared comprising about 8.5 partsby weight of a copolymer of about 65 parts, by weight of styrene andabout 35 parts by weight of butyl methacrylate; about 0.5 part by weightof a mixture of ortho and para toluene sulfonamide; and about 1 part byWeight of carbon black (Regal 300). The additive is available from theMonsanto Co. under the trademark Santicizer 9 and is a hard, dry solidhaving a melting point of about 221 F. After melting and preliminarymixing, the composition is fed into a rubber mill and thoroughly milledto yield a uniformly dispersed composition of the additive in thethermoplastic resin body. The resulting mixed composition is cooled andthen finely subdivided in a jet pulverizer to yield toner particleshaving an average particle size by weight percent of about 7 to about 12microns. About 2 parts by weight of the pulverized toner particles aremixed with about 0.05 part by weight of zinc stearate having a sizerange from about 0.5 to about 35 microns and about 98 parts by weight of813 Xerox carrier beads and substituted for the 813 developer in thetesting machine described in Example I. The treated toner dispenses welland high resolution images substantially free from background areobtained. Under substantially identical test conditions, it is foundthat the original standard Xerox 813 drive motor can be used and thatthe minimum fuser temperature at which legible copies are obtained afteran abrasion run of 5 revolutions of the abrading cylinder is about 550F. This is a reduction of about 60 F. from the fuser temperaturerequired for the control sample of Example I. No live embers or flamesare observed on copies emerging from the fuser. Micrograph studies ofthe reusable imaging surface after 10,000 cycles reveals less wear anddegradation of the surface than the imaging surface of Example 1.

Example IV A toner mixture is prepared comprising about 6.5 parts byweight of polystyrene; about 2 parts by weight of a polychlorinatedpolyphenyl and about 1.5 parts by weight of carbon black. The additiveis available from the Monsanto Co. under the trademark Aroclor 5460 andis a hard, dry solid having a melting range of about 208 F. to about 221F., a specific gravity (25 C./25 C.) of about 1.67 and a chlorinecontent of about 58.5 to 60.6

, percent by weight. After melting and preliminary mixing,

the composition is fed into a rubber mill and thoroughly milled to yielda uniformly dispersed composition of the additive in the thermoplasticresin body. The resulting mixed composition is cooled and then finelysubdivided in a jet pulverizer to yield toner particles having anaverage particle size by weight percent of about 10 to about 18 microns.About 1.5 parts by weight of the pulverized toner particles are mixedwith about 0.015 part by weight of iron oleate having a size range fromabout 5 to about 40 microns and about 98.5 parts by weight of 813 Xeroxcarrier beads and substituted for the 813 developer in the testingmachine described in Example I. The treated toner dispenses well andhigh resolution images substantially free from background are obtained.Under substantially identical test conditions, it is found that theoriginal standard Xerox 813 drive motor can be used and that the minimumfuser temperature at which legible copies are obtained after an abrasionrun of 5 revolutions of the abrading cylinder is about 550 F. This is areduction of 60 F. from the fuser temperature required for the controlsample of Example I. No live embers or flames are observed on copiesemerging from the fuser.

Example V A toner mixture is prepared comprising about 7.5 parts byweight of a copolymer of about 70 parts by weight styrene and about 30parts by weight of hexylmethacrylate; about 1.5 parts by weight ofpentaerythritol tetrabenzoate and about 1 part by weight of carbon black(Super Carbobar). The additive is a hard, dry solid having a meltingrange of about 201 to about 204 F. After melting and preliminary mixing,the composition is fed into a rubber, mill and thoroughly milled toyield a uniformly dispersed composition of the additive in thethermoplastic resin body. The resulting mixed composition is cooled andthen finely subdivided in a jet pulverizer to yield toner particleshaving an average particle size by weight percent of about 10 to about20 microns. About 1 part by weight of the pulverized toner particles aremixed With about 0.025 part by weight of cobalt palmitate having a sizerange from about 1 to about 30 microns and about 99 parts by weight of813 Xerox carrier beads and substituted for the 813 developer in thetesting machine described in Example I. The treated toner dispenses welland high resolution images substantially free from background areobtained. Under substantially identical test conditions, it is foundthat the original standard Xerox 813 drive motor can be used and thatthe minimum fuser temperature at which legible copies are obtained afteran abrasion run of revolutions of the abrading cylinder is about 490 F.This is a reduction of 120 F. from the fuser temperature required forthe control sample of Example I. No live embers or flames are observedon copies emerging from the fuser.

Example VI A toner mixture is prepared comprising about 7 parts byweight of a copolymer of 80 parts by weight of styrene and about 20parts by weight of isobutyl methacrylate and about 2 parts by weight ofpentaerythritol tetrabenzoate and about 1 part by weight of carbon black(Black Pearls L). The additive is a hard, dry solid having a meltingrange of about 201 F. to about 204 F. The toner mixture has an InstronCapillary Rheometer melt viscosity of about .5 poise at 260 F. Aftermelting and preliminary mixing, the composition is fed into a rubbermill and thoroughly milled to yield a uniformly dispersed composition ofthe additive in the thermoplastic resin body. The resulting mixedcomposition is cooled and then finely subdivided in a jet pulverized toyield toner particles having an average particle size by weight percentof about 10 to about 20 microns. About 1 part by weight of thepulverized toner particles are mixed with about 0.01 part by weight ofzinc stearate having a size range from about 0.04 to about 40 micronsand about 99 parts by weight of glass beads having an average diameterof about 500 microns and coated with a silicone terpolymer reactionproduct of butyl methacrylate, styrene and vinyl triethoxy silane andsubstituted for the 813 developer in the testing machine described inExample I. The treated toner dispenses extremely well and very highresolution images having negligible background are obtained. Undersubstantially identical test conditions, it is found that the originalstandard Xerox 813 drive motor can be used and that the minimum fusertemperature at which legible copies are obtained after an abrasion runof 5 revolutions of the abrading cylinder is about 520 F. This is areduction of 90 F. from the fuser temperature required for the controlsample of Example I. No live embers or flames are observed on copiesemerging from the fuser. Micrograph studies of the reusable imagingsurface after 10,000 cycles reveals less wear and degradation of thesurface than the imaging surface of Example I. No blocking is observedafter a sample of this toner is stored in an air circulating ovenmaintained at a temperature of about 110 F. for about 24 hours. Both thequality of images formed by this toner and its handling characteristicsare superior to all the other toners tested.

Example VII A toner mixture is prepared comprising about 7 parts byweight of isopropyl methacrylate resin; about 2 parts by weight ofglyceryl tribenzoate; and about 1 part by weight of carbon black. Theadditive is a hard, dry solid having a melting point of about F. Aftermelting and preliminary mixing, the composition is fed into a rubbermill and thoroughly milled to yield a uniformly dispersed composition ofthe additive in the thermoplastc resin body. The resulting mixedcomposition is cooled and then finely subdivided in a jet pulverizer toyield toner particles having an average particle size by weight percentof about 0.5 to about 1 micron. About 1 part by weight of the pulverizedtoner particles are mixed with about 0.05 part by weight of zinclinoleate having a size range from about 0.8 to about 25 microns andabout 99 parts by weight of uncoated glass carrier beads having anaverage particle size of about 500 microns and substituted for the 813developer in the testing machine described in Example I. The treatedtoner dispenses well and good images low in background are obtained.Under substantially identical test conditions, it is found the originalstandard Xerox 813 drive motor can be used and that the minimum fusertemperature at which legible copies are obtained after an abrasion runof 5 revolutions of the abrading cylinder is about 570 F. This is areduction of about 40 F. from the fuser temperature required for thecontrol sample of Example I. No live embers or flames are observed oncopies emerging from the fuser. Micrograph studies of the reusableimaging surface after 10,000 cycles reveals less wear and degradation ofthe surface than the imaging surface of Example I.

Example VIII A toner mixture is prepared comprising about 7 parts byweight of a copolymer of about 50 parts, by weight of propylmethacrylate and about 50 parts by weight of methacrylonitrile; about 2parts by Weight of a mixture of ortho and para toluene sulfonamide; andabout 1 part by weight of carbon black (Neo Spectra Mark II). Theadditive is available from the Monsanto Co. under the trademarkSanticizer 9 and is a hard, dry solid having a melting point of about221 F. After melting and preliminary mixing, the composition is fed intoa rubber mill and thoroughly milled to yield a uniformly dispersedcomposition of the additive in the thermoplastic resin body. Theresulting mixed composition is cooled and then finely subdivided in ajet pulverizer to yield toner particles having an average particle sizeby Weight percent of about 5 to about 16 microns. About 1 part by weightof the pulverized toner particles are mixed with about 0.06 part byweight of zinc stearate having a size range from about 0.5 to about 20microns and about 99 parts by weight of 813 Xerox carrier beads andsubstituted for the 813 developer in the testing machine described inExample I. The treated toner dispenses well and good resolution imagessubstantially free from background are obtained. Under substantiallyidentical test conditions, it is found that the original standard Xerox813 drive motor can be used and that the minimum fuser temperature atwhich legible copies are obtained after an abrasion run of 5 revolutionsof the abrading cylinder is about 580 F. This is a reduction of about 30F. from the fuser temperature required for the control sample of ExampleI. No live embers or flames are observed on copies emerging from thefuser. Micrograph studies of the reusable imaging surface after 10,000cycles reveals less wear and degradation of the surface than the imagingsurface of Example I.

Example IX A toner mixture is prepared comprising about 7.5 parts byweight of a copolymer of about 20 parts by weight of vinyl acetate andabout '80 parts by Weight of vinyl chloride; about 1.5 parts by Weightof pentaerythritol tetrabenzoate; and about 1 part by weight of carbonblack. After melting and preliminary mixing, the composition is fed intoa rubber mill and thoroughly milled to yield a uniformly dispersedcomposition of the additive in the thermoplastic resin body. Theresulting mixed composition is cooled and then finely subdivided in atSzegvari attritor to yield toner particles having an average particlesize by weight of about 10 to about 20 microns. About 2 parts by weightof the pulverized toner particles are mixed with about 0.1 part byweight of zinc stearate having a size range from about 0.5 to about 20microns and about 98 parts by weight of 813 Xerox carrier beads andsubstituted for the 813 developer in the testing machine described inExample I. The treated toner dispenses well and images substantiallyfree from background are obtained. Under substantially identical testconditions, it is found that the original standard Xerox 813 drive motorcan be used and that the minimum fuser temperature at which legiblecopies are obtained after an abrasion run of 5 revolutions of theabrading cylinder is about 560 F. This is a reduction of about 50 F.from the fuser temperature required for the control sample of Example I.No live embers or flames are observed on copies emerging from the fuser.

Example X A toner mixture is prepared comprising about 9 parts by weightof an ethyl methacrylate polymer; about 1 part by weight ofpentaerythritol tetrabenzoate and about 1 part by weight of carbonblack. After melting and preliminary mixing, the composition is fed intoa rubber mill and thoroughly milled to yield a uniformly dispersedcomposition of the additive in the thermoplastic resin body. Theresulting mixed composition is cooled and then finely subdivided in ajet pulverizer to yield toner particles having an average particle sizeby weight of about 5 to about 10 microns. About 1.5 parts by weight ofthe pulverized toner particles are mixed with about 0.01 part by weightof zinc stearte having a size range from about 0.5 to about 40 micronsand about 98.5 parts by weight of uncoated glass beads and substitutedfor the 813 developer in the testing machine described in Example I. Thetreated toner dispenses well and images substantially free frombackground are obtained. Under substantially identical test conditions,it is found that the original standard Xerox 813 drive motar can be usedand that the minimum fuser temperature at which legible copies areobtained after an abrasion run of 5 revolutions of the abrading cylinderis about 540 F. This is a reduction of about 70 F. from the fusertemperature required for the control sample of Example I. No live embersor flames are observed on copies emerging from the fuser.

Example XI A toner mixture is prepared comprising about 8 parts byweight of a copolymer of about 35 parts by weight vinyl acetate andabout 65 parts by weight of acrylonitrile; about 1 part by weight oftrimethylolethane tribenzoate and about 1 part by weight of carbonblack. The additive is a hard, dry solid having a melting point of about163 F. After melting and preliminary mixing, the composition is fed intoa rubber mill and thoroughly milled to yield a uniformly dispersedcomposition of the additive in the thermoplastic resin body. Theresulting mixed composition is cooled and then finely subdivided in ajet pulverizer to yield toner particles having an average particle sizeby weight of about 7 to about 12 microns. About 1 part by weight of thepulverized toner particles are mixed with about 0.04 part by weight ofzinc stearate having a size range from about '0.5 to about 20 micronsand about 99 parts by weight of glass beads having an average diameterof about 500 microns and coated with a silicone terpolymer reactionproduct of butyl methacrylate, styrene and vinyl triethoxy silane andsubstituted for the 815 developer in the testing machine described inExample I. The treated toner dispenses well and images substantiallyfree from background are obtained. Under substantially identical testconditions, it is found that the original standard Xerox 813 drive motorcan be used and that the minimum fuser temperature at which legiblecopies are obtained after an abrasion run of 5 revolutions of theabrading cylinder is about 560 F.

This is a reduction of about 50 F. from the fuser temperature requiredfor the control sample of Example I. No live embers or flames areobserved on copies emerging from the fuser.

Example XII A toner mixture is prepared comprising 7.5 parts by weightof a copolymer of about 25 parts of n-butyl methacrylate resin and about75 parts by weight of acrylonitrile resin; about 1.5 parts by weight ofglyceryl tribenzoate; and about 1 part by weight of carbon black. Aftermelting and preliminary mixing, the composition is fed into a rubbermill and thoroughly milled to yield a uniformly dispersed composition ofthe additive and pigment in the thermoplastic resin body. The resultingmixed composition is cooled and then finely subdivided in a high speedattritor to yield a toner particle size by Weight of about 5 to about 10microns. About 99 parts by weight of 813 Xerox carrier beads is mixedwith about 1 part by weight of toner and about 0.05 part by weight ofzinc stearate having a size range from about 0.5 to about 40 microns andsubstituted for the 813 developer in the testing machine described inExample I. The treated toner dispenses well and images substantiallyfree from background are obtained. Under substantially identicalconditions, it is found that the original standard Xerox 813 drive motorcan be used and that the minimum fuser temperature at which legiblecopies are obtained after an abrasion run of 5 revolutions of theabrading cylinder is about 545 F. This is a reduction of about 65 F.from the fuser temperature required for the control example of ExampleI. No live embers or flames are observed on copies emerging from thefuser.

Example XIII A toner mixture is prepared comprising about 5.5 parts byweight of a copolymer of about parts by weight of styrene and 10 partsby weight of isobutyl methacrylate, about 3.5 parts by weight ofpentaerythritol tetrabenzoate and about 1 part by weight of carbonblack. The additive is a hard, dry solid having a melting range of about201 to about 204 F. After melting and preliminary mixing in a BanburyMixer, the composition is fed into a rubber mill and thoroughly milledto yield a uniformly dispersed composition of the additive in thethermoplastic resin body. The resulting mixed composition is cooled andthen finely subdivided in a jet pulverizer to yield toner particleshaving an average particle size by weight percent of about 10 to 20microns. About 1 part by weight of the pulverized toner particles ismixed with about 0.01 part by weight of zinc stearate having a sizerange from about 0.5 to about 20 microns and about 99 parts by weight of500 microns uncoated glass carrier beads and substituted for the 813developer in the testing machine described in Example I. The treatedtoner dispenses well and high resolution images substantially free frombackground are obtained. Under substantially identical test conditions,it is found that the original standard Xerox 813 drive motor can be usedand that the minimum fuser temperature at which legible copies areobtained after an abrasion run of 5 revolutions of the abrading cylinderis about 510 F. This is a reduction of about 100 F. from the fusertemperature required for the control sample of Example I. No live embersor flames are observed on copies emerging from the fuser.

Example XIV A toner mixture is prepared comprising of about 5.5 parts byweight of copolymer of about 80 parts by weight styrene and about 20parts by weight of ethyl acrylate, and about 3.5 parts by weight of amixture of ortho and para toluene sulfonamide, and about 1.0 by weightof carbon black. The additive is available from the Monsanto Co. underthe trademark Santicizer 9 and is a hard, dry s l d having a meltingpoint of 221 F. After milling and preliminary mixing, the composition isfed into a rubber mill and thoroughly milled to yield a uniformlydispersed composition of the additive in the thermoplastic resin body.The resulting mixed composition is cooled and then finely subdivided ina jet pulverizer to yield toner particles having an average particlesize by Weight of about 10 to about 20 microns. About 1 part by weightof the pulverized toner particles are mixed with about 0.02 part byWeight of lead stearate having a size range from about 10 to about 35microns and about 99 parts by Weight of 81.3 carrier in the testingmachine described in Example I. The treated toner dispenses well andimages substantially free from background are obtained. Undersubstantially identical test conditions, it is found that the originalstandard Xerox 813 drive motor can be used and that the minimum fusertemperature at which legible copies are obtained after an abrasion runof 5 revolutions of the abrading cylinder is about 500 F. This is areduction of about 110 F. from the fuser temperature required for thecontrol sample of Example I. No live embers or flames are observed oncopies emerging from the fuser.

Example XV A toner mixture is prepared comprising about 7.5 parts ofcopolymer of about 80 parts by Weight of styrene and about 20 parts byweight isobutyl methacrylate and about 1.5 parts glyceryl tribenzoateand 1.0 part by weight carbon black. Glyceryl tribenzoate is a dry solidmanufactured by Velsicol Chemical Corporation with a molecular weight of404 and a melting point about 160 F. After melting and preliminarymixing, the composition is fed into a rubber mill and thoroughly milledto yield a uniformly dispersed composition of the additive in thethermoplastic resin body. The resulting mixed composition is cooled andthen finely subdivided in a jet pulverizer to yield toner particleshaving an average particle size by weight of about 8 to 22 microns.About 1 part by weight of the pulverized toner particles are mixed withabout 0.01 part by weight of zinc stearate having a size range fromabout 0.4 to about 40 microns and about 99 parts by weight of 813 Xeroxcarrier and substituted for the 813 developer in the testing machinedescribed in Example I. The treated toner dispenses Well and imagessubstantially free from background are obtained. Under substantiallyidentical test conditions, it is found that the original standard Xerox813 drive motor can be used and that the minimum fuser temperature atwhich legible copies are obtained after abrasion of 5 revolutions of theabrading cylinder is about 540 F. This is a reduction of 70 F. from thefuser temperature required for the con trol sample of Example I. No liveembers or flames are observed on copies emerging from the fuser.

Example XVI A toner mixture is prepared comprising about 8.0 parts byweight of a copolymer of about 70 parts by weight styrene and 30 partsby weight of vinyl acetate, about 1.0 part by weight oftrimethylolethane tribenzoate and about 1.0 part by weight of carbonblack. The additive is a hard, white crystalline solid having a meltingpoint of about 163 F. and a molecular weight of 432. After melting andmixing in a Banbury mixer and thoroughly rubber milling to yield auniformly dispersed composition of the additive in the thermoplasticresin body, the mixed composition is cooled and then pulverized in aSzegvari attritor to yield toner particles having an average particlesize of about 10 to microns. About 1 part by weight of the pulverizedtoner particles are mixed with about 0.03 part by weight of zincstearate having a size range from about 0.4 to about 40 microns andabout 99 parts by weight of 813 carrier in the test machine described inExample I. The treated toner dispenses well and images substantiallyfree from background are obtained. Under' substantially identical testconditions, it is found that the original standard Xerox 813 drive motorcan be used and that the minimum fuser temperature at which legiblecopies are obtained after an abrasion run of 5 revolutions of theabrading cylinder is about 550 F. This is a reduction of about 60 F.from the fuser temperature required for the control sample of Example I.No live embers or flames are observed on copies emerging from the fuser.

Example XVI'I A toner mixture is prepared comprising about 8.0 parts byWeight of a copolymer of about 85 parts by weight styrene and about 15parts by weight vinylidene chloride copolymer and about 1.0 part byweight of ethylene glycol dibenzoate and about 1.0 part by weight carbonblack. The additive is available from the C. P. Hall Co. under thetrademark Hallco 870 and is a hard, dry solid having a melting range ofabout 156 F. to about 164 F. After melting and preliminary mixing, thecomposition is fed into a rubber mill and thoroughly milled to yield auniformly dispersed composition of the additive in the thermoplasticresin body. The resulting mixed composition is cooled and then finelysubdivided in a jet pulverizer to yield toner particles having anaverage particle size by weight of about 8 to 14 microns. About 1 partby Weight of the pulverized toner particles are mixed with about 0.01part by Weight of zinc stearate having a size range from about 0.4 toabout 40 microns and about 99 parts by weight of 813 Xerox carrier beadsand substituted for the 813 developer in the testing machine describedin Example I. The treated toner dispenses well and images substantiallyfree from background are obtained. Under substantially identical testconditions, it is found that the original standard Xerox 813 drive motorcan be used and that the minimum fuser temperature at which legiblecopies are obtained after an abrasion run of 5 revolutions of theabrading cylinder is about 540 F. This is a reduction of 70 F. from thefuser temperature required for the control sample of Example I. No liveembers or flames are observed on copies emerging from the fuser.

Example XVIII A toner mixture is prepared comprising about 6.0 parts byweight of a copolymer of about 20 parts by weight styrene and aboutparts by weight of vinyl alcohol; and about 3.0 parts by Weight ofn-cyclohexyl p-toluene sulfonamide, and about 1.0 part by Weight ofcarbon black. The additive is available from the Monsanto C0. under thetrademark Santicizer 1H and is a hard water insoluble crystalline solid,heat stable to about 300 F. with a crystalline melting point of 186 F.After melting and preliminary mixing, the composition is fed into arubber mill and thoroughly milled to yield a uniformly dispersedcom-position of the additive in the thermoplastic resin body. Theresulting mixed composition is cooled and then finely subdivided in ajet pulverizer to yield toner particles having an average particle sizeby weight percent of about 10 to 20 microns. About 2 parts by weight ofthe pulverized toner particles are mixed with about 0.02 part by Weightof zinc palmitate having a size range from about 0.5 to about 35 micronsand about 98 parts by Weight of a coated carrier comprising glass beadscoated with ethyl cellulose coating and having an average diameter ofabout 600 microns and substituted for the 813 developer in the testingmachine described in Example I. The treated toner dispenses Well andimages substantially free from background are obtained. Undersubstantially identical test conditions, it is found that the originalstandard Xerox 813 drive motor can be used and that the minimum fusertemperature at Which-legible copies are obtained after an abrasion runof 5 revolutions of the abrading cylinder is about 560 F. This is areduction of 50 F. from the fuser temperature required for the controlsample of Example I. No live embers or flames are observed on copiesemerging from the fuser.

Example XIX A toner mixture is prepared comprising about 6.0 parts byweight of a copolymer of about 80 parts by Weight styrene, about 20parts by weight acrylonitrile and about 3.0 parts by Weight ofn-ethyl-p-toluene sulfonamide and about 1.0 part by weight of carbonblack. The additive is available from the Monsaonto Co. under thetrademark Santicizer 3 and is a hard, white solid with a melting pointof about 139 F. After melting and initial mixing, the composition is fedinto a rubber mill and thoroughly milled to yield a uniformly dispersedcomposition of the additive in the thermoplastic resin body. Theresulting mixed composition is cooled and then finely subdivided in ajet pul verizer to yield toner particles having an average particle sizeby weight of 10 to 20 microns. About 1 part by weight of the pulverizedtoner particles are mixed with about 0.04 part by wegiht of zincstearate having a size range from about 0.4 to about 40 microns andabout 99 parts by Weight of 813 Xerox carrier beads and substituted forthe 813 developer in the testing machine described in Example I. Thetreated toner dispenses well and images substantially free frombackground are obtained. Under substantially identical test conditions,it is found that the original standard Xerox 813 drive motor can be usedand that the minimum fuser temperature at which legible copies areobtained after an abrasion run of 5 revolutions of the abrading cylinderis about 560 F. This is a reduction of 50 F. from the fuser temperaturerequired for the control sample of Example I. 'No live embers or flamesare observed on copies emerging from the fuser.

Example XX A toner mixture is prepared comprising about 7.5 partscopolymer of about 80 parts by weight styrene and about 20 parts byWeight of isobutyl methacrylate and about 1.5 parts by Weight ofpentaerythritol tetrabenzoate and about 1.0 part by weight carbon black(Super Carbobar). The toner has a melt viscosity as measured on theInstron Capillary Rheometer of .5 poise at a temperature of about 280 F.The additive is a dry solid having a melting range of about 201 to about204 F. After melting and preliminary mixing, the composition is fed intoa rubber mill and thoroughly milled to yield a uniformly dispersedcomposition of the additive in the thermoplastic resin body. Theresulting mixed composition is cooled and then finely subdivided in aSzegvari attritor to yield toner particles having an average particlesize of about 10 to 20 microns. About one part of the toner is mixedwith,

about 0.03 part by weight of zinc stearate having a size range fromabout 0.5 to about 40 microns and about 99 parts of a coated carriercomprising glass beads coated with an ethyl cellulose coating and havingan average diameter of about 600 microns and is substituted for the 813developer in the testing machine described in Example I. The treatedtoner dispenses well and images substantially free from background areobtained. Under substantially identical test conditions, it is foundthat the original standard Xerox 813 drive motor can be used and thatthe minimum fuser temperature at which legible copies are obtained afteran abrasion run of 5 revolutions of the abrading cylinder is about 550F. This is a reduction of about 60 F. from the fuser temperaturerequired for the control sample of Example I. No live embers or flamesare observed on copies emerging from the fuser.

Example XXI A sample of the treated toner and carrier described inExample V is employed in the 813 Xerox copying machine described inExample I to make copies of a standard test image. Although the 813machine is again operaated at 11 copies per minute, the fusertemperature is set at about 490 F. The quality of fix of the toner imageis tested in a Taber Abraser, Model 174, available from the WelchScientific Co. About 20 cycles of the abraser is required to obtain animage density reduction of about 20 percent as measured on a Densichromreflection unit.

Example XXII A sample of the control toner and carrier described inExample I is employed to form toner images. The imaging and testingprocedure used is substantially identical to the procedure described inExample XXI. Less than about 2 cycles of the abraser is required toobtain an image density reduction of about 20 percent as measured on theDensichrom reflection unit. The deposited toner image is easilydestroyed by rubbing the images With a finger or thumb.

Example XXIII A control toner mixture is prepared comprising about 9parts by Weight of a mixture of ortho and para toluene sulfonamide and 1part by weight of Nigrosine SSB dye. The sulfonamide mixture isavailable under the trademark Santicizer 9 and is a hard, dry solidhaving a melting point of about 221 F. After melting a preliminarymixing, the composition is thoroughly milled to yield a uniformdispersion of dye and sulfonamide. The resulting mixed composition iscooled and finely subdivided in a Szegvari attritor to yield an averageparticle size by Weight percent of about 8 to about 15 microns. Theresulting toner is mixed with coated glass carrier beads and cascadedacross a negatively charged latent electrostatic image bearing surface.The deposited toner image is transferred to a paper sheet and fused atabout 305 -F. When the imaged paper sheet is folded, it is found thatthe toner images located along the crease tended to crack and crumble.When an imaged sheet formed by the processes described in Example III isfolded, no cracking or crumbling of the toner images located along thecrease is observed.

Example XXIV A control sample containing 1 part toner particlescontaining Santicizer 9 dyed with Amplast Black and having an averageparticle size of about 10 to about 20 microns and about 99 parts Xerox813 carrier particles is tumbled in a rotating cylindrical jar having aninside diameter of about 2.25 and a surface speed of about 140 feet perminute. An inspection of the developer mixture after about 50 hoursafter the test is initiated reveals a large quantity of undesirable finepowder.

Example XXV A toner mixture containing about 7.5 parts by weight of acopolymer of about parts by weight of styrene and about 20 parts byWeight of isobutyl methacrylate and about 1.5 parts by Weight Santicizer9 and about 1 part by weight of carbon black, and having an averageparticle size of about 10 to about 20 microns is mixed with about 99parts by weight of Xerox 813 carrier particles. The resulting developeris tumbled in the rotating cylindrical jar described in Example XXIV. Aninspection of the developer mixture 50 hours after the test is initiatedreveals substantially no undesirable powder.

Example XXVI A control toner mixture is prepared comprising about 7.5parts by weight of a copolymer of about 65 parts by weight of styreneand 35 parts by Weight of butylmethacrylate; about 1.5 parts by weightof polyethylene Wax; and about 1 part by Weight of carbon black (NeoSpectra Mark II). The Wax is available under the trademark Tenite 812A,sold by Eastman Kodak and is a dry solid having a melting range of about220 to about 230 F. After melting and preliminary mixing, thecomposition is fed into a rubber mill and thoroughly milled to yield auniformly dispersed composition of the wax in the thermoplastic resinbody. The resulting mixed composition is cooled with liquid nitrogen andthen finely subdivided in a Szegvari Attritor to yield toner particles21 having an average particle size of about to about 20 microns. Coolingbelow room temperature was necessary to avoid filming of the tonermaterial on the attritor parts. About one part of the toner is mixedwith about 99 parts of a coated carrier comprising glass beads coatedwith an ethyl cellulose coating and having an average diameter of about600 microns. The resulting developer is used to make 8,000 copies in an813 Xerox copying machine. The copies, particularly the copies made nearthe termination of the test, are characterized by very low densityimages and high background. An examination of the xerographic drum afterthe termination of the test reveals a heavy film of toner over thesurface of the drum.

Example XXVII A control toner mixture is prepared comprising about 7parts by weight of a compolymer of about 80 parts by weight styrene andabout 20 parts by weight of isobutyl methacrylate and about 2.0 parts byweight of polyethylene sebacate and about 1.0 part by weight of carbonblack. The additive is a dry solid having a melting point of about 167F. After melting and preliminary mixing, the composition is fed into arubbermill and thoroughly milled to yield a uniformly dispersedcomposition of the additive in the thermoplastic resin body. Theresulting mixed composition is cooled and then finely subdivided in ajet pulverized to yield toner particles having an average particle sizeby weight of about 10 to about 20 microns. About 1 part by weight of thepulverized toner particles are mixed with about 99 parts by weight of813 Xerox carrier beads and substituted for the 813 developer in thetesting machine described in Example I. The resulting developer is usedto make 10,000 copies in an 813 Xerox copying machine. The copies madenear the termination of the test are characterized by very low densityimages and high background. An examination of the xerographic drum afterthe termination of the test reveals a heavy film of the toner over thesurface of the drum resulting from poor toner cleanability.

' Example XXVIII A toner mixture is prepared comprising about 8 parts byweight of a copolymer of about 65 parts by weight of styrene and 35parts by weight of butylmethacrylate; about 1 part by weight ofpentaerythritol tetrabenzoate and about 1 part by weight of carbon black(Neo Spectra Mark II). The toner mixture has an Instron CapillaryRheometer melt viscosity of about .5 10- at 265 F. After melting andpreliminary mixing, the composition is fed into a rubber mill andthoroughly milled to yield a uniformly dispersed composition of theadditive in the thermoplastic resin body. The resulting mixedcomposition is cooled and then finely subdivided in a Szegvari attritorto yield toner particles having an average particle size of about 10 toabout 20 microns. About one part of the toner is mixed with about 0.01part by weight of zinc stearate having a size range from about 0.4 toabout 40 microns and about 99 parts of a coated carrier comprising glassbeads coated with an ethyl cellulose coating and having an averagediameter of about 600 microns. The resulting developer is used to make8,000 copies in an 813 Xerox copying machine. Substantially, all thecopies are characterized by sharp, high density images and lowbackground deposits. An examination of the xerographic drum after thetermination of the test reveals substantially imperceptible film of thetoner over the surface of the drum.

Example XXIX A control toner sample substantially identical to the tonerdescribed in Example VI is tested for its blocking temperature. The testprocedure involves the steps of initially heating the toner particles inan air circulating oven at about 100 F. for a 24 hour period and,thereafter, increasing the temperature in 5 increments every 22 24hours. The blocking temperature is that temperature at which a mildcrushing action with a spatula is required to restore any toneragglomerates formed to the original finely divided particulate form. Theblocking temperature of the control sample is about 125 F.

Example XXX A control toner mixture is prepared comprising about 7 partsby weight of a copolymer of about parts by weight of styrene and 20parts by Weight of isobutyl methacrylate; about 2 parts by weight ofethyl phthalyl ethyl glycolate; and about 1 part by weight of carbonblack (Black Pearls L). The ethyl phthalyl ethyl glycolate is availableunder the trademark S'anticizer E-15 and is a liquid. After melting andpreliminary mixing, the composition is fed into a rubber mill andthoroughly milled to yield a uniformly dispersed composition of the waxin the thermoplastic resin body. The resulting mixed composition iscooled with liquid nitrogen and then finely subdivided in a Szegvariattritor to yield toner particles having an average particle size ofabout 10 to about 20 microns. The toner particles are then testedaccording to the procedure described in Example XIV. The toner particlesblocked at the initial test temperature of F.

Example XXXI A control toner mixture is prepared comprising about 7parts by weight of a copolymer of about 80 parts by weight of styreneand 20 parts by weight of isobutyl methacrylate; about 2 parts by Weightof paraffin; and about 1 part by weight of carbon black (Black PearlsL). The parafiin is available under the trademark 4312 and is a drysolid having a melting range of about to about 143 F. After melting andpreliminary mixing, the composition is fed into a rubber mill andthoroughly milled to yield a uniformly dispersed composition of the waxin the thermoplastic resin body. The resulting mixed composition iscooled with liquid nitrogen and then finely subdivided in a Szegvariattritor to yield toner particles having an average particle size ofabout 10 to about 20 microns. The toner particles are then testedaccording to the procedure described in Example XIV. The toner particlesblocked at the initial test temperature of 100 F.

Example XXXII A control sample containing one part colored preformedtoner particles of the type described in Example VI having an averageparticle size of about 10 to about 20 microns is mixed with about 99'parts by weight of glass beads having an average particle diameter ofabout 400 microns and coated With ethyl cellulose and then cascadedacross an electrostatic image-bearing drum surface. The developed imageis then transferred by electrostatic means to a sheet of paper whereonit is fused by heat. The residual powder is removed from theelectrostatic imaging surface by a cleaning web of the type disclosed byW. P. Graft, Jr., et al. in US. Pat. 3,186,838. After the copyingprocess is repeated 25,000 times, the copies and electrostaticimage-bearing surface are examined for quality and Wear, respectively.The copies possess sharp line contrast and minimal backgrounddeposition. However, an examination of the imaging surface revealsnumerous scratches and the effects of erosive conditions.

Example XXXIII About 0.1 part of zinc stearate having a particle sizedistribution from 0.75 micron to about 40 microns is gently folded intoone part of a colored preformed toner particle of the type described inExample VI. The resulting developer mixture is then thoroughly milled ina Szegvari attritor for about 10 minutes. The developing procedure ofExample XXXII is repeated with a new drum and with the foregoing milledmixture substituted for the toner of Example XXXII at a relativehumidity of about 5 0 percent at 70 F. and at a relative humidity of 80percent at 80 F. Copies prepared with the milled sample possess higherdensity solid area coverage and cleaner background than copies preparedwith the control sample. Further, visual examination of theelectrostatic image-bearing surface reveals less wear than on thescratched image-bearing surface of Example XXXII. Considerably lesstorque is necessary to drive the drum when the stearate additive isemployed and a lower voltage is required to transfer the toner images toa receiving sheet.

Example XXXIV About 0.025 part of zinc stearate having a particle sizedistribution from about 0.75 micron to about 40 microns is gently foldedinto about parts of a colored preformed toner particle of the typedescribed in Example VI. The resulting mixture is then tumbled in asealed contaner for minutes. About one part of the tumbled mixture ismixed with 99 parts of ethyl cellulose coated carrier beads having anaverage particle size of about 400 microns. The resulting developermixture is employed in a cascade developing process as described inExample XXXII at a relative humidity of 50 percent at 70 F. and at arelative humidity of 80 percent at 80 F. The resulting fused tonerimages are denser under both humidity conditions than the imagesobtained in Example XXXIII.

The expression developer material as employed herein is intended toinclude electroscopic toner material or combinations of toner materialand carrier material.

Although specific materials and conditions are set forth in theforegoing examples, these are merely intended as illustrations of thepresent invention. Various other suitable thermoplastic toner resincomponents, additives, colorants, and development processes such asthose listed above may be substituted for those in the examples withsimilar results. Other materials may also be added to the toner orcarrier to sensitize, synerize or otherwise improve the fusingproperties or other desirable properties of the system.

Other modifications of the present invention will occur to those skilledin the art upon a reading of the present disclosure. These are intendedto be included within the scope of this invention.

What is claimed is:

1. A process for the preparation of a solid electrostatographicdeveloper material comprising providing finely-divided toner particlesuniformly electrostatically coated on a carrier surface capable ofretaining said toner particles by electrostatic attraction, said tonerparticles having a blocking temperature of at least about 110 F., a meltviscosity less than about 2.5 10- poise at temperatures up to about 450F., and comprising a colorant selected from the group consisting of apigment and a dye, a thermoplastic resin consisting essentially of avinyl polymer having a melting point of at least about 110 F., and about3 percent to about 65 percent by weight, based on the total weight ofsaid vinyl polymer, of a solid additive having a melting point betweenabout 115 F. and about 270 F. and selected from the group of organiccompounds having the general structures wherein R is selected from thegroup consisting of hydrogen, chlorine, bromine, aryl radicals, andalkyl radicals having from 1 to 6 carbon atoms and R and R" are 24selected from the group consisting of hydrogen, aryl radicals, and alkylradicals having from 1 to 12 carbon atoms,

and

Gi Cl 01m l wherein n represents a positive integer from 0 to 3inclusive and in has an average value from 0.5 to 2.5 inclusive andmixtures thereof; forming said finely-divided toner particles intoparticles having a size range of up to about 30 microns, and thereaftertumbling said particles with from about 0.02 percent to about 20 percentby weight, based on the weight of said particles, of at least one solid,stable hydrophobic metal salt of a fatty acid having a melting pointgreater than about 57 C. until said metal salt is uniformly mixed withand is available at the external surfaces of said particles.

2. A process according to claim 1 wherein said additive ispentaerythritol tetrabenzoate.

3. A process according to claim 1 wherein said finelydivided tonerparticles contain at least about 25 percent by weight, based on thetotal weight of said thermoplastic resin in said toner, of a styreneresin.

4. A process according to claim 1 wherein said solid, stable hydrophobicmetal salt of a fatty acid is zinc stearate.

5. A process according to claim 1 wherein said finelydivided low meltingtoner particles are uniformly electrostatically coated on the surface ofcarrier particles having an average particle diameter between about 50to about 1000 microns.

6. A process according to claim 1 wherein said developer materialcomprises about 1 part by weight of said finely-divided toner particlesand from about 10' to about 200 parts by weight of said carrierparticles.

7. A process for the preparation of a treated solid electrostatographictoner material comprising providing toner particles having a blockingtemperature of at least about F., a melt viscosity less than about 2.510 poise at temperatures up to about 450 F., and comprising a colorantselected from the group consisting of a pigment and a dye, athermoplastic resin consisting essentially of a vinyl polymer having amelting point of at least about 110 F., and from about 3 percent toabout 65 percent, based on the weight of said vinyl polymer, of a solidadditive having a melting point between about F. and about 270 F. andselected from the group of organic compounds having the generalstructure o Riot wherein n represents a positive integer from 3 to 7inclusive and R represents an organic moiety having from 3 to 12 carbonatoms;

wherein R is selected from the group consisting of hydrogen, chlorine,bromine, aryl radicals, and alkyl radicals having from 1 to 6 carbonatoms and R and R" are selected from the group consisting of hydrogen,aryl radicals, and alkyl radicals having from 1 to 12 carbon atoms,

sive and in has an average value from 0.5 to 2.5 inclusive, and mixturesthereof; forming said toner particles into particles having a size rangeof up to about 30 microns, and thereafter tumbling said particles withfrom about 0.002 percent to about 20 percent by weight, based on theWeight of said toner particles, of at least one solid, stablehydrophobic metal salt of a fatty acid until said metal salt isuniformly mixed with and is available at the external surfaces of saidparticles.

8. A process according to claim 7 wherein said solid additive ispentaerythritol tetrabenzoate and said metal salt is zinc stearate.

References Cited 5 UNITED STATES PATENTS 3,653,893 4/1972 Jacknow et a1.252-62.1 3,417,019 12/1968 Beyer 252,'62.1 3,931,374 1/1966 Serambi25262.1

NORMAN G. TORCHIN, Primary Examiner J. P. BRAMMER, Assistant Examiner

